how is the kinetic energy of a moving car affected if
a) its mass is tripled
b) its velocity becomes one-fourth

Dear Student ,
(a)When the kinetic energy of a moving car is affected if its mass is tripled then ,kinetic energy becomes ,
$E_k\text{'}=\frac{1}{2}\left(3m\right)v^2=3\times \frac{1}{2}m{v}^2=3E_k$
So the kinetic energy becomes three times of its initial .
(b) Now when the velocity becomes one fourth then ,kinetic energy becomes ,

$E_k"=\frac{1}{2}m{\left(\frac{v}{4}\right)}^2=\frac{1}{16}\times \frac{1}{2}m{v}^2=\frac{1}{16}{E}_k$
Kinetic energy becomes 1/16 time of its initial .

Regards